Question 1: Define an exothermic reaction and explain how it affects the surroundings.

Answer: An exothermic reaction releases heat to the surroundings, causing the temperature to increase.

Question 2: Describe what a reaction profile illustrates about the energy changes during a chemical reaction.

Answer: A reaction profile shows the energy changes over the course of a reaction, including activation energy and the energy difference between reactants and products.

Question 3: Explain the difference between an endothermic and an exothermic reaction in terms of energy.

Answer: An endothermic reaction absorbs energy from the surroundings, causing the surroundings to cool down, while an exothermic reaction releases energy.

Question 1: A chemical reaction releases 150 kJ of energy. If the reaction involves 50 grams of reactant, what is the energy released per gram? (Use the formula: energy per gram = total energy / mass).

Answer: 3 kJ per gram

Question 2: If the activation energy of a reaction is 80 kJ/mol and the total energy change is -150 kJ/mol, what is the net energy change? (Indicate whether it's exothermic or endothermic).

Answer: Net energy change = -150 kJ/mol; the reaction is exothermic.

Question 1: Describe a simple experiment to compare the temperature change of an exothermic and an endothermic reaction. Include variables to control and safety precautions.

Answer: Students can react substances like sulfur and calcium chloride in water, measuring temperature changes with a thermometer. Variables to control include the amount of reactants and water temperature. Safety precautions involve wearing goggles and gloves, handling chemicals carefully, and working in a well-ventilated area.

Question 2: Identify two variables that could affect the energy change in a reaction and explain how they influence the reaction profile.

Answer: Variables include the temperature of reactants and the concentration of reactants. Higher temperature can increase reaction rate and energy release, while higher concentration can increase the reaction's energy change.

Question 1: A reaction shows a decrease in energy from reactants to products and releases heat to the surroundings. Describe what this indicates about the reaction profile and the type of reaction.

Answer: This indicates an exothermic reaction with a reaction profile that dips below the energy level of reactants, releasing energy.

Question 1: Explain how the shape of a reaction profile can provide information about the activation energy and the overall energy change of a reaction. Include the significance of the peak and the difference in height between reactants and products.

Answer: The peak of the reaction profile represents the activation energy required for the reaction to proceed. A higher peak indicates a higher activation energy, meaning the reaction needs more energy to start. The difference in height between the reactants and the products shows whether the reaction is exothermic (products lower than reactants) or endothermic (products higher). Understanding this shape helps predict reaction speed and energy efficiency.

Question 1: Describe how reaction profiles are important in the development of new fuels or explosives. Include considerations of energy release and safety.

Answer: Reaction profiles help scientists understand how much energy is released or absorbed, which is crucial in designing fuels and explosives. A reaction with a high energy release can be useful as a fuel or explosive but must be carefully controlled for safety. Understanding activation energy also helps in developing safer handling and storage procedures.